Topical 20% benzocaine (Hurricaine, Beutlich, Inc., Niles, Ill.) spray is frequently used for oral anesthesia before upper endoscopy. Side effects attributed to this agent are exceedingly rare. The author reports one of these rare complications, drug-induced methemoglobinemia, in a patient with methemoglobin reductase deficiency. The mechanisms for the development of methemoglobinemia and its treatment are reviewed.